General Knowledge - Physics - Discussion

Mercury is used in thermometers as opposed to water because of a few simple reasons.

1. While mercury is a liquid, it is doesn't have the same properties as water, therefore it won't condensate at the top of the thermometer, making the reading of temperature more accurate.

2. It relies on thermal expansion meaning the molecular bonds will expand with heat and contract with cold. This is why the mercury fluctuates according to temperature.

3. It's melting point is -38.83°C (water is only 0 °C) and doesn't boil until 356.73 °C (water boils at 100 °C) which made mercury a better candidate to read temperature since it's liquid stage goes a lot farther than water.

4. Mercury's silver appearance, makes it easy to read temperatures at just a glance.

Mercury is still used in some thermometers but because of its toxicity levels, it is gradually being replaced by alcohol or electronic thermometers.

Different reasons for this and they are listed below:.

It is liquid across a very broad temperature range, making it very versatile.

It is metal, and thus has a relatively stable coefficient of expansion, and it only needs one calibration temperature.

It has a fairly high coefficient of expansion, making the slightest change in temperature very visible and thus making it excellent for use in analog displays (i.e. A physical thermometer).

It does not cling to the sides of tube. It has a visible meniscus.

Unlike water it does not expand upon solidification and will not break the glass tube. It has a high boiling point of 357 degree celsius.

The answer is mercury is used in barometer because of having a higher density than water as we required a huge tube in case of water.

The same reason why it is used in thermometer is the high coefficient of expansion and bright visibility.

But the options given above have no coefficient of thermal expansion. So the answer is Visibility.

I think the answer should be C ie mercury have comparably small specific heat capacity. Means in lower temperature also it ll show its level. Mg specific heat is 140J/kg/k water has 4180J/kg/k. If visibility is matter then we add any color substance to water and then we can use water. But is not right. The answer should be changed to C.

As a scholar in physics the answer should be C because mercury has comparably small specific heat capacity means in lower temperature and it will show its level.

So if visibility is matter then we can add any color substance to water and then we can use water but this is wrong anywhere. So the answer should be c.

If water were used instead of mercury, the height of the column required would be very large. The density of mercury being much more than that of water, it expands lesser and thus can be used in manageable tubes. There is nothing limiting us from using water instead of mercury except the height of the tube.

I agree with what Sourajit said, the long height resulting due to the density of water being lower than that of mercury would be unmanageable, so the answer to this question should be changed, its not because of visibility factor.

The density of Mercury and tube length are related to barometer only.

In thermometer, Mercury is used because it has a higher coefficient of thermal expansion, that's why a small change in temp can be measured.

Mercury is used in thermometers because it has high coefficient of thermal expansion. So, any slight change of temperature is easily noticed and also it is clearly visible in glass tube as compared to water.

Hi I guess some people want to say option A but by mistake they are writing it as option C as they are giving the explanation of specific heat which is option A not C.

I think correct answer is option A.